High speed magnetic coil for magneto-optical head

ABSTRACT

The conductor pattern of a magnetic head coil includes a spiral coil pattern to which a current can be supplied to flow around the magnetic field generation center, and a conductor pattern which is formed outside the coil pattern and cannot receive a current so as to flow around the magnetic field generation center. Letting S be the distance from the outer edge of the outermost periphery of the coil pattern, and P be the pitch, a conductor occupation ratio R of a conductor pattern formed outside the coil pattern simultaneously satisfies inequalities 1 to 3, and the conductor pattern does not form any closed loop surrounding the coil pattern in a first region A 1  given by inequality 1: 
     Inequality 1: 0≦R≦0.3 in the first region A 1  where 
     0≦S≦1.5P 
     Inequality 2: 0≦R≦0.8 in a second region A 2  where 
     1.5P&lt;S≦6.0P 
     Inequality 3: 0.3&lt;R≦1 in a third region A 3  where 
     6.0P&lt;S

TECHNICAL FIELD

The present invention relates to a magnetic head coil suitable forrecording an information signal at a high speed, a magnetic head usingit, and a magneto-optical recording apparatus.

BACKGROUND ART

A conventionally known magneto-optical recording apparatus applies amagnetic field modulated by an information signal to a magneto-opticalrecording medium such as a magneto-optical disk, and irradiates themedium with light to record an information signal. This magneto-opticalrecording apparatus comprises a magnetic head for applying a magneticfield. The magnetic head may be one of various types of heads. Forexample, FIG. 17 is a perspective view showing a magnetic head disclosedin Japanese Laid-Open Patent Application No. 4-74335, and FIG. 18 is asectional view showing the magnetic head.

Reference numeral 50 denotes a flat coil component (to be referred to asa coil hereinafter) formed from a flexible printed wiring board; and 51,a core made of a magnetic material such as ferrite. The coil 50 isconstituted by a flexible base 52 made of polyimide or polyester, aspiral coil pattern 53 serving as a conductor pattern made of a copperfoil formed on the base 52, and terminals 54 a and 54 b. The coil 50 isbonded to the core 51 with an adhesive 55.

The terminals 54 a and 54 b of the coil 50 are connected to the magnetichead drive circuit of a magneto-optical recording apparatus. Themagneto-optical recording apparatus comprises an optical head. To recordan information signal, the optical head irradiates the magneticrecording layer of a magneto-optical recording medium with a laser beamso as to converge the laser beam to a small light spot. At the sametime, the magnetic head drive circuit supplies a current to the coilpattern 53 to generate a magnetic field modulated by an informationsignal from the center of the coil pattern 53, and vertically appliesthe magnetic field to the laser beam irradiation position of themagnetic recording layer.

Conventionally, like this prior art, only a conductor pattern serving asa path for positively supplying a current, i.e., a conductor patternnecessary for an electrical function is formed on components usingconductor patterns including a flat coil component for a magnetic head.

In recent years, as demands have arisen for a higher information signalrecording speed, the flat coil component used in the magnetic head mustbe downsized. Along with this, the dimensional precision and flatness ofthe flat coil component must be increased to adjust the relativeposition to the optical head and the distance from the magneto-opticalrecording medium at higher precision. The magnetic field must beaccurately, efficiently applied to the light spot position on themagnetic recording layer of the magneto-optical recording medium.However, the above-described flat coil is low in rigidity and mechanicalstrength, readily deforms in manufacturing a magnetic head, and isdifficult to be adjusted to an accurate position. Thus, the abovedemands cannot be met. This problem will be explained in detail.

To more efficiently generate a magnetic field in the above magnetichead, the coil pattern 53 must be formed very close to the core 51. Forthis purpose, the base 52 must be as thin as possible. To efficientlyapply a magnetic field to the magneto-optical recording medium, thesurface of the coil 50 must be brought very close to the magneto-opticalrecording medium.

Although not described in the above reference, the base 52 constitutingthe coil 50 is made of a 20-μm thick polyimide sheet. Since the thinresin material sheet is very flexible, the coil 50 is insufficient inrigidity, posing the following problem in manufacturing a magnetic head.

More specifically, in bonding the coil 50 and the core 51, the coil 50cannot resist an operating force and readily deforms, e.g., bends at aportion where no coil pattern 53 is formed. As a result, the attachingposition of the coil 50 is not accurately determined, causing an error.The relative position to the optical head deviates, so an informationsignal cannot be normally recorded.

A conductor pattern for connecting the coil pattern to the terminal 54 bis formed to protrude from the base 52 on a surface of the coil 50facing the core 51. Thus, the surface of the coil 50 facing the core 51is not flat. In bonding the coil 50 to the core 51, part of a surface ofthe coil 50 facing the magneto-optical disk readily deforms, e.g.,protrudes or inclines. This inhibits the surface of the coil 50 facingthe magneto-optical recording medium from coming very close to themagneto-optical recording medium so as to efficiently apply a magneticfield.

To increase the information signal recording speed, the magnetic fieldmodulation frequency must be increased. However, the RF loss on the core51 and coil pattern 53 increases in almost proportion to the modulationfrequency, so that the temperature of the magnetic head rises. Themagnetic material such as ferrite forming the core 51 decreases insaturation flux density Bs along with the temperature rise. As themagnetic field modulation frequency increases, the saturation fluxdensity Bs of ferrite forming the core 51 decreases to be equal to theinternal flux density of the core 51. If the magnetic field modulationfrequency further increases, the internal flux density of the core 51decreases together with the saturation flux density Bs, and the strengthof a magnetic field generated by the magnetic head also decreases. As aresult, a magnetic field applied to the magneto-optical recording mediumweakens, failing to record an information signal.

If the temperature of the magnetic head exceeds the heat resistancelimit of its building member, deformation or electrical insulationfailure may occur.

Under these circumstances, an increase in modulation frequency islimited, and the information signal recording speed cannot be furtherincreased.

DISCLOSURE OF INVENTION

In the present invention, a flat coil (to be referred to as a coilhereinafter) for a magnetic head is made up of at least a coil patternserving as a conductor pattern made of a conductive material film, and aterminal for supplying a current to the coil pattern. The coil patternis a spiral conductor pattern capable of supplying a current so as toflow around the magnetic field generation center. In the presentinvention, a region where this coil pattern is formed is defined as an“effective region” where an effective current contributing to generationof a magnetic field can be supplied. A region outside the coil patternwhere at least the conductor pattern capable of supplying a current soas to flow around the magnetic field generation center is not formed isdefined as an “ineffective region”. In the following description,conductor patterns formed in the ineffective region except for aconductor pattern serving as a current supply path to the coil pattern,such as a conductor pattern for connecting terminals to each other and aterminal to the coil pattern, will be referred to as a “dummy pattern”.

The present invention has been made to overcome the conventionaldrawbacks, and has as its object to provide a flat coil for a magnetichead in which a conductor pattern is formed in the ineffective region,and a conductor occupation ratio R (ratio of the total area of allconductor patterns formed from a conductive material film in a givenregion, to the total area of the region) is defined within apredetermined range in accordance with the distance from the coilpattern, thereby improving the mechanical strength, flatness, anddimensional precision without degrading the electrical characteristicsof the coil, a magnetic head using the flat coil, and a magneto-opticalrecording apparatus.

The present inventors have made extensive studies to find that the aboveproblem can be solved when, letting S be the distance from the outeredge of the coil pattern (outer edge of the effective region), P be thepitch (or minimum value when the pitch is not constant) of the coilpattern, and R be the conductor occupation ratio, the ineffective regionoutside the effective region is divided into a plurality of regions onthe basis of the distance S, conductor patterns are laid out in therespective regions so as to simultaneously satisfy inequalities 1, 2,and 3, and the conductor pattern in a first region A1 does not form anyclosed loop:

Inequality 1: 0≦R≦0.3 in the first region A1 where

0≦S≦1.5P

Inequality 2: 0≦R≦0.8 in a second region A2 where

1.5P<S≦6.0P

Inequality 3: 0.3<R≦1 in a third region A3 where

6.0P<S

More specifically, the conductor occupation ratio R of a conductorpattern formed in the ineffective region is set low near the coilpattern, and set high apart from the coil pattern. In this case, theelectrical characteristics and mechanical strength of the coil can beconsistent with each other. If necessary, a dummy pattern not serving asa current supply path to the coil pattern is formed in the ineffectiveregion such that the conductor occupation ratio R of the conductorpattern in the ineffective region simultaneously satisfies inequalities1, 2, and 3. This will be explained in more detail.

If the area of a conductor pattern formed in the first region A1 of theineffective region that is nearest to the coil pattern is large, a largeelectrostatic capacitance is generated between the coil pattern and theconductor pattern formed in the first region A1. Such largeelectrostatic capacitance decreases the change rate of a currentsupplied to the coil to decrease the magnetic field inversion speed ingenerating a magnetic field modulated by the magnetic head. As a result,an information signal becomes difficult to record at a high speed. Inthe manufacture of a coil or after long-term use, the insulationreliability between the conductor pattern formed in the first region A1and the coil pattern degrades. To prevent this, no conductor pattern isformed or the conductor occupation ratio R of the conductor pattern issuppressed to 0.3 or less in the first region A1.

If the conductor pattern forms near the coil pattern a closed loopsurrounding the coil pattern, a current (eddy current) reverse to thesupply current to the coil pattern is induced in the conductor patternin supplying a current to the coil pattern and generating a magneticfield modulated by the magnetic head. Consequently, the change of amagnetic field to be generated is canceled, failing in normalinformation signal recording. To prevent this, it is preferable that theconductor pattern in the first region A1 be discontinuously formed bydividing the conductor pattern into two or more in the spiral directionof the coil pattern, and all the divided conductor patterns have aninterval of 0.2P or more. This suppresses generation of an eddy currentin the conductor pattern.

The second region A2 is also a range where the influence of a magneticfield generated by supplying a current to the coil pattern is exerted,not to such an extent as the first region A1. If the conductoroccupation ratio R of a conductor pattern formed in the second region A2exceeds 0.8, a generated eddy current or the electrostatic capacitancewith the coil pattern degrades coil characteristics. To prevent this, noconductor pattern is formed or the conductor occupation ratio R of theconductor pattern is suppressed to 0.8 or less in the second region A2,as represented by inequality 2.

In the third region A3, if the conductor occupation ratio R of theconductor pattern is 0.3 or less, no reinforcing effect is substantiallyattained. If the conductor occupation ratio R of a conductor patternformed in the third region A3 is lower than 0.6 times the conductoroccupation ratio of the coil pattern, the current density in plating isbiased to concentrate a current on the coil pattern in manufacturingconductive and coil patterns by plating. The conductor pattern in thethird region A3 becomes thinner than the coil pattern, so the coilpattern undesirably protrudes. To efficiently generate a magnetic field,the conductor occupation ratio of the coil pattern is desirably 0.5 ormore. Hence, as represented by inequality 3, the conductor occupationratio R of the conductor pattern is set to 0.3<R≦1 in the third regionA3. This relaxes local concentration of the current density in plating,and averages the metal ion diffusion rate within the pattern.Accordingly, the film thickness of the conductor pattern formed byplating is made uniform to prevent the coil pattern from protruding.

Note that the conductor occupation ratio R is the ratio, to the totalarea of each region, of the total area of all conductor patternsincluding a dummy pattern formed in the region and a conductor patternfor connecting terminals to each other and a terminal to a coil pattern.When the region includes a portion where no conductor pattern can beformed, e.g., a hole formed in part of the coil, this area is notincluded in the total area of the region. If the ineffective regionincludes a portion where the width is partially equal to or smaller thanthe pitch P of the coil pattern and the conductor pattern is difficultto form, a conductor pattern need not always be formed at this portion.

The conductor pattern (dummy pattern) formed in the ineffective regionmay have an arbitrary shape. Especially when a linear, slit-like,dot-like, or polygonal conductor pattern is periodically laid out, theconductor occupation ratio R of the conductor pattern is averaged overeach region to decrease the thermal expansion and contractiondistributions. Thus, the flatness, warpage, and dimensional precision ofa conductive circuit can be improved, and the mechanical strength can bereinforced. Also when plating is applied, the current density and iondiffusion rate are averaged to make the plating film thickness moreuniform. The layout period (pitch) of such conductor pattern may beconstant or random. By setting the period (pitch) to be equal to or morethan the pitch P of the coil pattern and equal to or less than 5P, thefilm thickness can be made more uniform.

Since the peripheral edge of the coil (edge portion such as the outeredge of the coil or the peripheral edge of a hole formed in the coil)requires a sufficient mechanical strength, the conductor pattern (dummypattern) is desirably formed along the peripheral edge of the coil.However, if the conductor pattern is laid out to form a closed loop atthe peripheral edge of a hole formed in the inner portion of the coilpattern to insert a magnetic pole or a hole serving as alight-transmitting portion, an eddy current generated in the conductorpattern cancels a magnetic field to be generated. For this reason, atleast a conductor pattern forming a closed loop is not laid out at theperipheral edge of the hole formed at the inner portion of the coilpattern.

It is preferable that the conductor pattern formed at the peripheraledge of the coil have a band shape, and its width be equal to or morethan the pitch P of the coil pattern and equal to or less than 4P. Anarrower conductor pattern does not substantially reinforce theperipheral edge; or a wider conductor pattern increases the diffusionrate of metal ions in a plating solution and increases the thickness tobe much larger than the coil pattern in forming a conductor pattern byplating. If this band-like conductor pattern is formed to be coupled toanother conductor pattern in the ineffective region, the coil isreinforced and made more flat. The conductor pattern need not always beformed even at the peripheral edge of the coil as far as the intervalbetween this peripheral edge and the outer edge of the coil pattern isequal to or less than the pitch P of the coil pattern. In this manner,the conductor pattern along the peripheral edge of the coil need notalways be completely continuous to form a closed loop, but may bepartially disconnected.

A positioning portion such as a circular or oval hole or a recess formedin the outer periphery of the coil is formed in the ineffective region,and a conductor pattern is formed at the peripheral edge of thepositioning portion. This increases the mechanical strength around thepositioning portion. In the following description, this conductorpattern formed at the peripheral edge of the positioning portion will becalled a “guide pattern”. Forming the guide pattern prevents the coilfrom deforming in fitting the positioning portion of the coil on alocking member attached to another building member such as the slider ofthe magnetic head. The relative positional precision to the optical headcan further increase.

The conductor pattern formed in the ineffective region dissipates heatgenerated by the coil pattern or core formed in the effective region,thereby preventing the temperature rise of the magnetic head. A magnetichead having a heat dissipation member in tight contact with theconductor pattern can obtain high heat dissipation efficiency.

In the ineffective region, a conductor pattern having an appropriateshape can be formed at an appropriate position in accordance with thepurpose. If all conductor patterns are formed such that their conductoroccupation ratios R satisfy inequalities 1, 2, and 3, the mechanicalstrength of the coil increases without degrading the electricalcharacteristics of the coil. All conductor patterns including the coilpattern have almost the same thickness, which prevents some of theconductor patterns from protruding from the coil surface. In bonding theupper surface of the coil to another member such as a core, the lowersurface (surface facing the magneto-optical recording medium) of thecoil does not protrude or incline. As a result, the coil can be arrangedat high precision so as to satisfactorily decrease the distance betweenits lower surface and the surface of the magneto-optical recordingmedium in manufacturing a magnetic head. The magnetic field can beefficiently applied to the magneto-optical recording medium.

The present invention implements a magnetic head excellent in heatdissipation characteristics which can increase the relative positionalprecision between the coil and the optical head and the distanceprecision from the magneto-optical recording medium, while the coil isdownsized to reduce its inductance. This allows setting the magneticfield modulation frequency to 8 MHz or more, and increasing theinformation signal recording speed.

A flat coil component for the magnetic head according to the presentinvention can be manufactured by a combination of pattern formation andetching by photolithography, plating, and the like. In particular, whenthe present invention is applied to a coil formed from a conductorpattern having a thickness larger than the width of the coil pattern,i.e., having a high aspect ratio and a large film thickness,photolithography using a liquid photosensitive resin is optimum. Thatis, a thick resin setting pattern having a high aspect ratio is formedusing a liquid photosensitive resin, and a conductor pattern as aconductive material film is formed as almost thick as the resin settingpattern by plating. If the set substance of the liquid photosensitiveresin is not removed but is used as an insulating member, a flat coilcomponent for a magnetic head can be manufactured in which the conductorpattern is as almost thick as the insulating member, which prevents theconductor pattern from protruding. Alternately, the set substance of theliquid photosensitive resin may be removed, and then an insulatingmember made of a thermosetting resin or the like may be buried to almostthe same thickness as the conductor pattern. The insulating member maybe formed thicker than the conductor pattern so as to cover the end faceof the conductor pattern. Especially when the insulating member isformed as thick as or thicker than the conductor pattern on the uppersurface side of the coil that is bonded to another member, the conductorpattern does not protrude, and the coil surface becomes very flat. Thisfurther prevents the lower surface of the coil from protruding orinclining upon bonding.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view showing a coil according to Example 1 of thepresent invention;

FIGS. 2A and 2B are plan views showing the coil according to Example 1of the present invention;

FIGS. 3A and 3B are plan views showing a coil according to Example 2 ofthe present invention;

FIGS. 4A and 4B are plan views showing a coil according to Example 3 ofthe present invention;

FIGS. 5A and 5B are plan views showing a coil according to Example 4 ofthe present invention;

FIGS. 6A and 6B are plan views showing a coil according to Example 5 ofthe present invention;

FIGS. 7A and 7B are plan views showing a coil according to Example 6 ofthe present invention;

FIGS. 8A and 8B are plan views showing a coil according to Example 7 ofthe present invention;

FIGS. 9A and 9B are plan views showing a coil according to Example 8 ofthe present invention;

FIGS. 10A and 10B are plan views showing a coil according to Example 9of the present invention;

FIGS. 11A and 11B are views, respectively, showing a magnetic headaccording to Example 1 of the present invention;

FIGS. 12A and 12B are views, respectively, showing a magnetic headaccording to Example 9 of the present invention;

FIGS. 13A and 13B are views, respectively, showing a magnetic headaccording to Example 10 of the present invention;

FIGS. 14A and 14B are views, respectively, showing a magnetic headaccording to Example 11 of the present invention;

FIG. 15 is a block diagram showing the arrangement of a magneto-opticalrecording apparatus according to Example 1 of the present invention;

FIG. 16 is a block diagram showing the arrangement of a magneto-opticalrecording apparatus according to Example 2 of the present invention;

FIG. 17 is a perspective view showing a conventional magnetic head formagneto-optical recording;

FIG. 18 is a sectional view showing the conventional magnetic head formagneto-optical recording;

FIGS. 19A and 19B are plan views showing the structure of a coilaccording to Comparative Example 1; and

FIGS. 20A and 20B are plan views showing the structure of a coilaccording to Comparative Example 2.

BEST MODE OF CARRYING OUT THE INVENTION

Examples of the present invention will be described in detail below.Note that the present invention is not limited by the examples.

EXAMPLE 1

FIGS. 11A and 11B show the structure of a magnetic head 1. FIG. 11A is aside sectional view, and FIG. 11B is a bottom view. The magnetic head 1is constituted by a core 12 made of a magnetic material such as ferrite,a coil 13, and a slider 14 which mounts them. Reference numeral 4denotes a magneto-optical disk serving as a magneto-optical recordingmedium.

The core 12 is made of a magnetic material such as ferrite with a flatshape, and its center has a projecting magnetic pole p1 with a prismshape. The coil 13 is flat, and its center has a square hole h1. Themagnetic pole p1 of the core 12 is inserted in the hole h1. The coil 13is mounted on the slider 14 together with the core 12. The slider 14 ismade of a resin material, ceramic material, or the like, and has asliding surface As or floating surface Af for sliding on orfloating/gliding above the magneto-optical disk 4, so as to face themagneto-optical disk 4.

FIGS. 1, 2A, and 2B show the detailed structure of the coil 13. FIG. 1is a sectional view, FIG. 2A is a plan view when viewed from the top,and FIG. 2B is a plan view when viewed from the bottom. The coil 13 ismade up of a base 15, a spiral coil pattern 16 a, a dummy pattern 17 a,an insulating member 18 a, terminals 19 b and 19 a, a protection coat 20a, which patterns 16 a and 17 a, member 18 a, terminals 19 b and 19 a,and coat 20 a are formed on the upper surface side (side facing the core12) of the base 15, a spiral coil pattern 16 b, a dummy pattern 17 b, aninsulating member 18 b, and a protection coat 20 b, which patterns 16 band 17 b, member 18 b, and coat 20 b are formed on the lower surfaceside (side facing the magneto-optical disk 4) of the base 15. The regionwhere the coil patterns 16 a and 16 b are formed is an effective region.A current flowing around the magnetic field generation center (hole h1)can be supplied to the coil patterns 16 a and 16 b. The region outsidethe effective region where conductor patterns such as the dummy patterns17 a and 17 b and the terminals 19 a and 19 b are formed is anineffective region. A current flowing around the magnetic fieldgeneration center (hole h1) is not supplied to the conductor patternsformed in the ineffective region.

The coil patterns 16 a and 16 b, dummy patterns 17 a and 17 b, andterminals 19 a and 19 b as conductor patterns are made of a conductivematerial film such as a copper film, and have a thickness H of 50 μm.The coil patterns 16 a and 16 b have a width W of 25 μm, and a constantpitch P of 40 μm from the inner to outer peripheries. The insulatingmembers 18 a and 18 b are made of a nonconductive material film, e.g., aphotosensitive resin or thermosetting resin film used in forming thecoil patterns 16 a and 16 b. The insulating members 18 a and 18 b areequal in thickness to conductor patterns such as the coil patterns 16 aand 16 b. In this manner, the thicknesses of the conductor pattern andinsulating member 18 a and those of the conductor pattern and insulatingmember 18 b are set equal on the upper and lower surface sides of thecoil 13, respectively. This prevents conductor patterns such as the coilpatterns 16 a and 16 b from protruding from the upper and lower surfacesof the coil 13. The surface of the coil 13 can, therefore, be made flat.In FIGS. 2A and 2B, all black portions are conductor patterns made of aconductive material film, and all surrounding blank portions are theinsulating member 18 a (upper surface side) or 18 b (lower surfaceside).

The coil patterns 16 a and 16 b are connected at an inner peripheralportion via a through hole 21 a. The terminal 19 a is connected to theouter peripheral portion of the coil pattern 16 a, whereas the terminal19 b is connected to that of the coil pattern 16 b via a through hole 21b. The terminals 19 a and 19 b can supply a DC current to the coilpatterns 16 a and 16 b.

The base 15 is formed to electrically insulate the coil patterns 16 aand 16 b, and is made of a thin resin material sheet such as a polyimidesheet. An interval Tb (almost equal to the thickness of the base 15 inExample 1) between the coil patterns 16 a and 16 b is 20 μm. Theprotection coats 20 a and 20 b are thin films or sheets made of anonconductive material such as a resin material and prevent damage andcorrosion of the surfaces of the coil patterns 16 a and 16 b. Theprotection coats 20 a and 20 b have a thickness Tc of 20 μm.

Since the dummy patterns 17 a and 17 b are formed in the ineffectiveregions around the coil patterns 16 a and 16 b, the thickness T of thecoil 13 is uniformly 160 μm on almost the entire surface. Compared to acase in which no dummy pattern is formed, the mechanical strength of thecoil 13 increases. The coil 13 is satisfactorily rigid, and does notdeform, e.g., bend when the coil 13 is bonded to the core 12, mounted onthe slider 14, and fixed in manufacturing a magnetic head. Since theupper surface (surface facing the core 12) of the coil 13 is flat, itslower surface (surface facing the magneto-optical disk 4) does notdeform, e.g., protrude or incline upon bonding to the core 12.

When the coil 13 is formed from a plurality of coil patterns, likeExample 1, the interval Tb between these coil patterns must be 70 μm orless, and desirably, 35 μm or less. This can increase the coil patternspace factor (ratio of the conductor pattern to the remaining portion onthe section) to efficiently generate a magnetic field. The coil patternand the conductor pattern (dummy pattern) formed in the ineffectiveregion are desirably formed such that the thickness T of the coil 13 isset to 70 μm or more.

If coil patterns are formed on both the upper and lower surface sides ofthe coil, and conductor patterns (dummy patterns) are formed in theineffective regions on the two sides, like Example 1,expansion/contraction caused by temperature changes occurs to almost thesame degree on the upper and lower surface sides of the coil, and thecoil does not deform, e.g., warp.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Example 1 will be described in detail.

In Example 1, the pitch P of the coil patterns 16 a and 16 b is 40 μm. Aregion where a distance S from the outer edge of each of the coilpatterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined as a firstregion A1 on both the upper and lower surface sides of the coil 13 inaccordance with inequalities 1, 2, and 3; a region where the distance Ssatisfies 60 μm<S≦240 μm, as a second region A2; and a region where thedistance S satisfies 240 μm<S, as a third region A3. In FIGS. 2A and 2B,a broken line B1 represents the boundary between the first and secondregions A1 and A2, and a broken line B2 represents the boundary betweenthe second and third regions A2 and A3.

The dummy patterns 17 a and 17 b are formed in the respective regions asfollows. No dummy pattern is formed in the first region A1 on both theupper and lower surface sides of the coil 13. Hence, the conductoroccupation ratio R of the conductor pattern is 0 in the first region A1on both the upper and lower surface sides. The dummy patterns 17 a and17 b are formed from striped conductor patterns in the second and thirdregions A2 and A3 on both the upper and lower surface sides of the coil13. The striped conductor patterns have a width of 40 μm and a pitch of60 μm. The terminals 19 a and 19 b are formed in the third region A3 onthe upper surface side of the coil 13. The conductor occupation ratio Rof the conductor pattern is about 0.60 in the second region A2 on boththe upper and lower surface sides of the coil 13, about 0.63 in thethird region A3 on the upper surface side, and about 0.60 in the thirdregion A3 on the lower surface side.

In this way, the ineffective region is divided into a plurality ofregions on the basis of the distance S from the outer edge of the coilpattern (outer edge of the effective region). Conductor patterns arelaid out in the respective regions so as to simultaneously satisfyinequalities 1, 2, and 3. In the first region A1, no conductor patternforms any closed loop. Accordingly, the reinforcing effect can beobtained without degrading the electrical characteristics of the coil.

EXAMPLE 2

Example 2 of the present invention will be described. A magnetic head inExample 2 has the same structure as that in Example 1 shown in FIG. 11,and a description thereof will be omitted. FIGS. 3A and 3B show thedetailed structure of a coil 13 in Example 2. FIG. 3A is a plan viewwhen viewed from the top, and FIG. 3B is a plan view when viewed fromthe bottom.

The structure except for conductor patterns formed in the ineffectiveregion is the same as that in Example 1 shown in FIGS. 1 and 2, and adescription thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Example 2 will be described.

Also in Example 2, a region where the distance S from the outer edge ofeach of coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined asa first region A1 on both the upper and lower surface sides of the coil13 in accordance with inequalities 1, 2, and 3; a region where thedistance S satisfies 60 μm<S≦240 μm, as a second region A2; and a regionwhere the distance S satisfies 240 μm<S, as a third region A3. In FIGS.3A and 3B, a broken line B1 represents the boundary between the firstand second regions A1 and A2, and a broken line B2 represents theboundary between the second and third regions A2 and A3.

The dummy patterns are formed in the respective regions as follows. Nodummy pattern is formed in the first region A1 on both the upper andlower surface sides of the coil 13. For this reason, the conductoroccupation ratio R of the conductor pattern is 0 in the first region A1on both the upper and lower surface sides. The dummy patterns 17 a and17 b are formed from square-dot-like conductor patterns in the secondand third regions A2 and A3 on both the upper and lower surface sides ofthe coil 13. The square-dot-like conductor patterns have a side lengthof 60 μm and a layout pitch of 80 μm. Terminals 19 a and 19 b are formedin the third region A3 on the upper surface side of the coil 13. Theconductor occupation ratio R of the conductor pattern is about 0.56 inthe second region A2 on both the upper and lower surface sides of thecoil 13, about 0.59 in the third region A3 on the upper surface side,and about 0.56 in the third region A3 on the lower surface side.

EXAMPLE 3

Example 3 of the present invention will be described. A magnetic head inExample 3 has the same structure as that in Example 1 shown in FIGS. 11Aand 11B, and a description thereof will be omitted. FIGS. 4A and 4B showthe detailed structure of a coil 13 in Example 3. FIG. 4A is a plan viewwhen viewed from the top, and FIG. 4B is a plan view when viewed fromthe bottom.

The structure except for conductor patterns formed in the ineffectiveregion is the same as that in Example 1 shown in FIGS. 1, 2A, and 2B,and a description thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Example 3 will be described.

Also in Example 3, a region where the distance S from the outer edge ofeach of coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined asa first region A1 on both the upper and lower surface sides of the coil13 in accordance with inequalities 1, 2, and 3; a region where thedistance S satisfies 60 μm<S≦240 μm, as a second region A2; and a regionwhere the distance S satisfies 240 μm<S, as a third region A3. In FIGS.4A and 4B, a broken line B1 represents the boundary between the firstand second regions A1 and A2, and a broken line B2 represents theboundary between the second and third regions A2 and A3.

The dummy patterns are formed in the respective regions as follows. Nodummy pattern is formed in the first region A1 on both the upper andlower surface sides of the coil 13. Therefore, the conductor occupationratio R of the conductor pattern is 0 in the first region A1 on both theupper and lower surface sides. The dummy patterns 17 a and 17 b areformed from square-matrix-like conductor patterns in the second andthird regions A2 and A3 on both the upper and lower surface sides of thecoil 13. The square-matrix-like conductor patterns have a width of 40 μmand a pitch of 100 μm. Terminals 19 a and 19 b are formed in the thirdregion A3 on the upper surface side of the coil 13. The conductoroccupation ratio R of the conductor pattern is about 0.64 in the secondregion A2 on both the upper and lower surface sides of the coil 13,about 0.67 in the third region A3 on the upper surface side, and about0.64 in the third region A3 on the lower surface side.

EXAMPLE 4

Example 4 of the present invention will be described. A magnetic head inExample 4 has the same structure as that in Example 1 shown in FIGS. 11Aand 11B, and a description thereof will be omitted. FIGS. 5A and 5B showthe detailed structure of a coil 13 in Example 4. FIG. 5A is a plan viewwhen viewed from the top, and FIG. 5B is a plan view when viewed fromthe bottom.

The structure except for conductor patterns formed in the ineffectiveregion is the same as that in Example 1 shown in FIGS. 1, 2A, and 2B,and a description thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Example 4 will be described.

Also in Example 4, a region where the distance S from the outer edge ofeach of coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined asa first region A1 on both the upper and lower surface sides of the coil13 in accordance with inequalities 1, 2, and 3; a region where thedistance S satisfies 60 μm<S≦240 μm, as a second region A2; and a regionwhere the distance S satisfies 240 μm<S, as a third region A3. In FIGS.5A and 5B, a broken line B1 represents the boundary between the firstand second regions A1 and A2, and a broken line B2 represents theboundary between the second and third regions A2 and A3.

The dummy patterns 17 a and 17 b are formed in the respective regions asfollows. No dummy pattern is formed in the first region A1 on both theupper and lower surface sides of the coil 13. The conductor occupationratio R of the conductor pattern is 0 in the first region A1 on both theupper and lower surface sides. The dummy patterns 17 a and 17 b areformed from striped conductor patterns in the second and third regionsA2 and A3 on both the upper and lower surface sides of the coil 13. Thestriped conductor patterns have a width of 115 μm and a pitch of 150 μm.Terminals 19 a and 19 b are formed in the third region A3 on the uppersurface side of the coil 13. The conductor occupation ratio R of theconductor pattern is about 0.77 in the second and third regions A2 andA3 on both the upper and lower surface sides of the coil 13.

EXAMPLE 5

Example 5 of the present invention will be described. A magnetic head inExample 5 has the same structure as that in Example 1 shown in FIGS. 11Aand 11B, and a description thereof will be omitted. FIGS. 6A and 6B showthe detailed structure of a coil 13 in Example 5. FIG. 6A is a plan viewwhen viewed from the top, and FIG. 6B is a plan view when viewed fromthe bottom.

The structure except for conductor patterns formed in the ineffectiveregion is the same as that in Example 1 shown in FIGS. 1, 2A, and 2B,and a description thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Example 5 will be described.

Also in Example 5, a region where the distance S from the outer edge ofeach of coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined asa first region A1 on both the upper and lower surface sides of the coil13 in accordance with inequalities 1, 2, and 3; a region where thedistance S satisfies 60 μm<S≦240 μm, as a second region A2; and a regionwhere the distance S satisfies 240 μm<S, as a third region A3. In FIGS.6A and 6B, a broken line B1 represents the boundary between the firstand second regions A1 and A2, and a broken line B2 represents theboundary between the second and third regions A2 and A3.

The dummy patterns 17 a and 17 b are formed in the respective regions asfollows. No dummy pattern is formed in the first region A1 on both theupper and lower surface sides of the coil 13. Hence, the conductoroccupation ratio R of the conductor pattern is 0 in the first region A1on both the upper and lower surface sides. The dummy patterns 17 a and17 b are formed from striped conductor patterns in the second and thirdregions A2 and A3 on both the upper and lower surface sides of the coil13. The striped conductor patterns have a width of 40 μm and a pitch of80 μm. In the third region A3, the dummy patterns 17 a and 17 b arefurther formed from 70-μm wide band-like conductor patterns formed alongthe outer edge of the coil 13. The band-like conductor pattern along theouter edge and the striped conductor pattern are coupled to each other.Terminals 19 a and 19 b are formed in the third region A3 on the uppersurface side of the coil 13. The conductor occupation ratio R of theconductor pattern is about 0.50 in the second region A2 on both theupper and lower surface sides of the coil 13, about 0.55 in the thirdregion A3 on the upper surface side, and about 0.52 in the third regionA3 on the lower surface side.

EXAMPLE 6

Example 6 of the present invention will be described. A magnetic head inExample 6 has the same structure as that in Example 1 shown in FIGS. 11Aand 11B, and a description thereof will be omitted. FIGS. 7A and 7B showthe detailed structure of a coil 13 in Example 6. FIG. 7A is a plan viewwhen viewed from the top, and FIG. 7B is a plan view when viewed fromthe bottom.

The structure except for conductor patterns formed in the ineffectiveregion is the same as that in Example 1 shown in FIGS. 1, 2A, and 2B,and a description thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Example 6 will be described.

Also in Example 6, a region where the distance S from the outer edge ofeach of coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined asa first region A1 on both the upper and lower surface sides of the coil13 in accordance with inequalities 1, 2, and 3; a region where thedistance S satisfies 60 μm<S≦240 μm, as a second region A2; and a regionwhere the distance S satisfies 240 μm<S, as a third region A3. In FIGS.7A and 7B, a broken line B1 represents the boundary between the firstand second regions A1 and A2, and a broken line B2 represents theboundary between the second and third regions A2 and A3.

The dummy patterns 17 a and 17 b are formed in the respective regions asfollows. No dummy pattern is formed in the first and second regions A1and A2 on both the upper and lower surface sides of the coil 13. Thus,the conductor occupation ratio R of the conductor pattern is 0 in thefirst and second regions A1 and A2 on both the upper and lower surfacesides. In the third region A3 on both the upper and lower surface sidesof the coil 13, the dummy patterns 17 a and 17 b are formed from stripedconductor patterns having a width of 40 μm and a pitch of 80 μm, and70-μm wide band-like conductor patterns formed along the outer edge ofthe coil 13. The band-like conductor pattern along the outer edge andthe striped conductor pattern are coupled to each other. Terminals 19 aand 19 b are formed in the third region A3 on the upper surface side ofthe coil 13. The conductor occupation ratio R of the conductor patternis about 0.55 in the third region A3 on the upper surface side of thecoil 13, and about 0.52 in the third region A3 on the lower surfaceside.

EXAMPLE 7

Example 7 of the present invention will be described. A magnetic head inExample 7 has the same structure as that in Example 1 shown in FIGS. 11Aand 11B, and a description thereof will be omitted. FIGS. 8A and 8B showthe detailed structure of a coil 13 in Example 7. FIG. 8A is a plan viewwhen viewed from the top, and FIG. 8B is a plan view when viewed fromthe bottom.

The structure except for conductor patterns formed in the ineffectiveregion is the same as that in Example 1 shown in FIGS. 1, 2A, and 2B,and a description thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Example 7 will be described.

Also in Example 7, a region where the distance S from the outer edge ofeach of coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined asa first region A1 on both the upper and lower surface sides of the coil13 in accordance with inequalities 1, 2, and 3; a region where thedistance S satisfies 60 μm<S≦240 μm, as a second region A2; and a regionwhere the distance S satisfies 240 μm<S, as a third region A3. In FIGS.8A and 8B, a broken line B1 represents the boundary between the firstand second regions A1 and A2, and a broken line B2 represents theboundary between the second and third regions A2 and A3.

The dummy patterns 17 a and 17 b are formed in the respective regions asfollows. In the first region A1 on both the upper and lower surfacesides of the coil 13, the dummy patterns 17 a and 17 b are formed from aplurality of conductor patterns laid out in the spiral direction of thecoil patterns 16 a and 16 b. The conductor patterns have a width of 25μm and a length of 60 μm, and the interval between respective conductorpatterns is 30 μm. The interval between this conductor pattern and theouter edge of the coil pattern 16 a or 16 b is 35 μm. The conductoroccupation ratio R of the conductor pattern is about 0.28 in the firstregion A1. In the second and third regions A2 and A3 on both the upperand lower surface sides of the coil 13, the dummy patterns 17 a and 17 bare formed from striped conductor patterns. The striped conductorpatterns have a width of 40 μm and a pitch of 80 μm. In the third regionA3, the dummy patterns 17 a and 17 b are further formed from 70-μm wideband-like conductor patterns formed along the outer edge of the coil 13.The band-like conductor pattern along the outer edge and the stripedconductor pattern are coupled to each other. Terminals 19 a and 19 b areformed in the third region A3 on the upper surface side of the coil 13.The conductor occupation ratio R of the conductor pattern is about 0.50in the second region A2 on both the upper and lower surface sides of thecoil 13, about 0.55 in the third region A3 on the upper surface side,and about 0.52 in the third region A3 on the lower surface side.

EXAMPLE 8

Example 8 of the present invention will be described. A magnetic head inExample 8 has the same structure as that in Example 1 shown in FIGS. 11Aand 11B, and a description thereof will be omitted. FIGS. 9A and 9B showthe detailed structure of a coil 13 in Example 8. FIG. 9A is a plan viewwhen viewed from the top, and FIG. 9B is a plan view when viewed fromthe bottom.

The structure except for conductor patterns formed in the ineffectiveregion is the same as that in Example 1 shown in FIGS. 1, 2A, and 2B,and a description thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Example 8 will be described.

Also in Example 8, a region where the distance S from the outer edge ofeach of coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined asa first region A1 on both the upper and lower surface sides of the coil13 in accordance with inequalities 1, 2, and 3; a region where thedistance S satisfies 60 μm<S≦240 μm, as a second region A2; and a regionwhere the distance S satisfies 240 μm<S, as a third region A3. In FIGS.9A and 9B, a broken line B1 represents the boundary between the firstand second regions A1 and A2, and a broken line B2 represents theboundary between the second and third regions A2 and A3.

The dummy patterns 17 a and 17 b are formed in the respective regions asfollows. In the first region A1 and second region A2 on both the upperand lower surface sides of the coil 13, the dummy patterns 17 a and 17 bare formed from a plurality of radial conductor patterns. The conductorpatterns have a width of 100 μm and a length of 205 μm, and the intervalbetween respective conductor patterns is, 70 to 120 μm. The intervalbetween this conductor pattern and the outer edge of the coil pattern 16a or 16 b is 35 μm. On both the upper and lower surface sides, theconductor occupation ratio R of the conductor pattern is about 0.25 inthe first region A1, and about 0.55 in the second region A2. In thethird region A3 on both the upper and lower surface sides of the coil13, the dummy patterns 17 a and 17 b are formed from striped conductorpatterns having a width of 40 μm and a pitch of 80 μm, and 70-μm wideband-like conductor patterns formed along the outer edge of the coil 13.The band-like conductor pattern along the outer edge and the stripedconductor pattern are coupled to each other. Terminals 19 a and 19 b areformed in the third region A3 on the upper surface side of the coil 13.The conductor occupation ratio R of the conductor pattern is about 0.55in the third region A3 on the upper surface side of the coil 13, andabout 0.52 in the third region A3 on the lower surface side.

EXAMPLE 9

Example 9 of the present invention will be described. FIGS. 12A and 12Bshow the structure of a magnetic head 1. FIG. 12A is a side sectionalview, and FIG. 12B is a bottom view. The magnetic head 1 is constitutedby a core 12 made of a magnetic material such as ferrite, a coil 13, anda slider 14 which mounts them. Reference numeral 4 denotes amagneto-optical disk serving as a magneto-optical recording medium.

The core 12 is made of a magnetic material such as ferrite with a flatshape, and its center has a projecting magnetic pole p1 with a prismshape. The coil 13 is flat, and its center has a square hole h1. Themagnetic pole p1 of the core 12 is inserted in the hole h1. The coil 13is mounted on the slider 14 together with the core 12. The slider 14 ismade of a resin material, ceramic material, or the like, and has asliding surface As or floating surface Af for sliding on orfloating/gliding above the magneto-optical disk 4, so as to face themagneto-optical disk 4.

The slider 14 has locking members 29, 30, and 31 projecting from theattaching surface of the coil 13. The coil 13 has positioning portions23, 24, and 25. The positioning portions 23 and 24 are circular holes,and the positioning portion 25 is a U-shaped recess formed in the outeredge of the coil 13. The coil 13 is attached to the slider 14 by fittingthe positioning portions 23, 24, and 25 on the locking members 29, 30,and 31 of the slider 14.

FIGS. 10A and 10B show the detailed structure of the coil 13. FIG. 10Ais a plan view when viewed from the top, and FIG. 10B is a plan viewwhen viewed from the bottom. The coil 13 is flat and made up of a base15, a spiral coil pattern 16 a, a dummy pattern 17 a, guide patterns 26a, 27 a, and 28 a, an insulating member 18 a, terminals 19 b and 19 a, aprotection coat 20 a, which patterns 16 a, 17 a, 26 a, 27 a, and 28 a,member 18 a, terminals 19 b and 19 a, and coat 20 a are formed on theupper surface side (side facing the core 12) of the base 15, a spiralcoil pattern 16 b, a dummy pattern 17 b, guide patterns 26 b, 27 b, and28 b, an insulating member 18 b, and a protection coat 20 b, whichpatterns 16 b, 17 b, 26 b, 27 b, and 28 b, member 18 b, and coat 20 bare formed on the lower surface side (side facing the magneto-opticaldisk 4) of the base 15. The coil patterns 16 a and 16 b are formed in aneffective region, and a current flowing around the magnetic fieldgeneration center (hole h1) can be supplied to the coil patterns 16 aand 16 b. The dummy patterns 17 a and 17 b, guide patterns 26 a, 27 a,28 a, 26 b, 27 b, and 28 b, and terminals 19 a and 19 b are formed in anineffective region, and a current flowing around the magnetic fieldgeneration center (hole h1) is not supplied to them.

The coil patterns 16 a and 16 b, dummy patterns 17 a and 17 b, guidepatterns 26 a, 27 a, 28 a, 26 b, 27 b, and 28 b, and terminals 19 a and19 b as conductor patterns are made of a conductive material film suchas a copper film, and have a thickness H of 50 μm. The coil patterns 16a and 16 b have a constant pitch P of 40 μm from the inner to outerperipheries, and a width W of 25 μm. The insulating members 18 a and 18b are made of a nonconductive material film, e.g., a photosensitiveresin or thermosetting resin material film used in forming the coilpatterns 16 a and 16 b. The insulating members 18 a and 18 b are equalin thickness to conductor patterns such as the coil patterns 16 a and 16b. In this fashion, the thicknesses of the conductor pattern andinsulating member 18 a and those of the conductor pattern and insulatingmember 18 b are set equal on the upper and lower surface sides of thecoil 13, respectively. This prevents conductor patterns such as the coilpatterns 16 a and 16 b from protruding from the upper and lower surfacesof the coil 13. The surface of the coil 13 can, therefore, be made flat.In FIGS. 10A and 10B, all black portions are conductor patterns made ofa conductive material film, and all surrounding blank portions are theinsulating member 18 a (upper surface side) or 18 b (lower surfaceside).

The coil patterns 16 a and 16 b are connected at an inner peripheralportion via a through hole 21 a. The terminal 19 a is connected to theouter peripheral portion of the coil pattern 16 a, whereas the terminal19 b is connected to that of the coil pattern 16 b via a through hole 21b. The terminals 19 a and 19 b can supply a DC current to the coilpatterns 16 a and 16 b.

The base 15 is formed to electrically insulate the coil patterns 16 aand 16 b, and is made of a thin resin material sheet such as a polyimidesheet. An interval Tb (almost equal to the thickness of the base 15 inExample 9) between the coil patterns 16 a and 16 b is 20 μm. Theprotection coats 20 a and 20 b are thin films or sheets made of anonconductive material such as a resin material and prevent damage andcorrosion of the surfaces of the coil patterns 16 a and 16 b. Theprotection coats 20 a and 20 b have a thickness Tc of 20 μm.

Since the dummy patterns 17 a and 17 b are formed in the ineffectiveregions around the coil patterns 16 a and 16 b, the thickness T of thecoil 13 is uniformly 160 μm on almost the entire surface. Compared to acase in which no dummy pattern is formed, the mechanical strength of thecoil 13 increases. The coil 13 is rigid enough, and does not deform,e.g., bend when the coil 13 is bonded to the core 12, mounted on theslider 14, and fixed in manufacturing a magnetic head. Since the uppersurface (surface facing the core 12) of the coil 13 is flat, its lowersurface (surface facing the magneto-optical disk 4) does not deform,e.g., protrude or incline upon bonding to the core 12.

When the coil 13 is formed from a plurality of coil patterns, likeExample 9, the interval Tb between these coil patterns must be 70 μm orless, and desirably 35 μm or less. This can increase the coil patternspace factor (ratio of the conductor pattern to the remaining portion onthe section) to efficiently generate a magnetic field. The coil patternand the conductor pattern (dummy pattern) formed in the ineffectiveregion are desirably formed such that the thickness T of the coil 13 isset to 70 μm or more.

If coil patterns are formed on both the upper and lower surface sides ofthe coil, and conductor patterns (dummy patterns) are formed in theineffective regions on the two sides, like Example 9,expansion/contraction caused by temperature changes occurs to almost thesame degree on the upper and lower surface sides of the coil, and thecoil does not deform, e.g., warp.

The conductor patterns, i.e., dummy patterns 17 a and 17 b and guidepatterns 26 a 27 a, 28 a, 26 b, 27 b, and 28 b formed in the ineffectiveregion in Example 9 will be described in detail.

In Example 9, the pitch P of the coil patterns 16 a and 16 b is 40 μm. Aregion where the distance S from the outer edge of each of the coilpatterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined as a firstregion A1 on both the upper and lower surface sides of the coil 13 inaccordance with inequalities 1, 2, and 3; a region where the distance Ssatisfies 60 μm<S≦240 μm, as a second region A2; and a region where thedistance S satisfies 240 μm<S, as a third region A3. In FIGS. 10A and10B, a broken line B1 represents the boundary between the first andsecond regions A1 and A2, and a broken line B2 represents the boundarybetween the second and third regions A2 and A3.

The dummy patterns are formed in the respective regions on the upper andlower surface sides as follows. No dummy pattern is formed in the firstregion A1 on both the upper and lower surface sides of the coil 13.Hence, the conductor occupation ratio R of the conductor pattern is 0 inthe first region A1 on both the upper and lower surface sides. The dummypatterns 17 a and 17 b are formed from striped conductor patterns in thesecond and third regions A2 and A3 on both the upper and lower surfacesides of the coil 13. The striped conductor patterns have a width of 40μm and a pitch of 80 μm. In the third region, the dummy patterns 17 aand 17 b are further formed from 70-μm wide band-like conductor patternsformed along the outer edge of the coil 13. The band-like conductorpattern along the outer edge and the striped conductor pattern arecoupled to each other. The guide patterns 26 a and 27 a are formed atthe peripheral edges of the positioning portions 23 and 24 in the thirdregion A3 on the upper surface side of the coil 13, and the guidepattern 28 a is formed at the peripheral edge of the positioning portion25 in the second and third regions A2 and A3. The guide patterns 26 band 27 b are formed at the peripheral edges of the positioning portions23 and 24 in the third region A3 on the lower surface side of the coil13, and the guide pattern 28 b is formed at the peripheral edge of thepositioning portion 25 in the second and third regions A2 and A3. Theseguide patterns 26 a, 27 a, 28 a, 26 b, 27 b, and 28 b have a 70-μm wideband shape. The terminals 19 a and 19 b are formed in the third regionA3 on the upper surface side of the coil 13.

The conductor occupation ratio R of the conductor pattern is about 0.50in the second region A2 on both the upper and lower surface sides of thecoil 13, about 0.55 in the third region A3 on the upper surface side ofthe coil 13, and about 0.52 in the third region A3 on the lower surfaceside.

As described above, also in Example 9, the ineffective region is dividedinto a plurality of regions on the basis of the distance S from theouter edge of the coil pattern (outer edge of the effective region).Conductor patterns are laid out in the respective regions so as tosimultaneously satisfy inequalities 1, 2, and 3. In the first region A1,no conductor pattern forms any closed loop. Accordingly, the reinforcingeffect can be obtained without degrading the electrical characteristicsof the coil.

If the guide patterns 26 a, 27 a, 28 a, 26 b, 27 b, and 28 b are notformed, and the peripheries of the positioning portions 23, 24, and 25are made from only the base 15 and insulating members 18 a and 18 b, theperipheries of the positioning portions 23, 24, and 25 are weak, cannotresist an operating force, and readily deform in fitting the positioningportions 23, 24, and 25 on the locking members 29, 30, and 31 of theslider 14 and attaching the coil 13 to the slider 14 during themanufacture of a magnetic head.

In Example 9, however, the guide patterns 26 a, 27 a, 28 a, 26 b, 27 b,and 28 b made of a conductive material film are formed at the peripheraledges of the positioning portions 23, 24, and 25. Thus, sufficientstrength can be ensured to prevent deformation.

A method of manufacturing the coil 13 according to Example 9 will beexplained. Formation of the coil 13 can adopt a pattern formation methodusing photolithography. In this case, an exposure mask can be formed athigh positional precision for both guide and coil patterns. Using thismask makes constant the relative position of the guide pattern to thecoil pattern, and substantially prevents any errors and manufacturingvariations.

The coil 13 having the guide patterns 26 a, 27 a, 28 a, 26 b, 27 b, and28 b is irradiated from one direction with a carbon dioxide gas laser orexcimer laser beam to perform laser processing. Then, the base 15 andinsulating members 18 a and 18 b are removed from inner portionssurrounded by the guide patterns 26 a, 27 a, 28 a, 26 b, 27 b, and 28 b,thereby forming holes and a recess, which serve as the positioningportions 23, 24, and 25. This processing method selectively removes onlya resin material as the constituent material of the base 15 andinsulating members 18 a and 18 b. The guide patterns 26 a, 27 a, 28 a,26 b, 27 b, and 28 b made of a conductive material film such as a copperfilm are not influenced by this processing, and serve as laserbeam-shielding masks. By emitting a beam to ranges slightly larger thanthe positioning portions 23, 24, and 25, the base can be removed fromonly inner portions surrounded by the guide patterns 26 a, 27 a, 28 a,26 b, 27 b, and 28 b.

According to the manufacturing method, the formation positions and sizesof the positioning portions 23, 24, and 25 are determined by the guidepatterns 26 a, 27 a, 28 a, 26 b, 27 b, and 28 b formed in advance. Evenif the attaching position of the coil 13 to a processing apparatus iserroneous, the positioning portions 23, 24 and 25 are free from theinfluence of any error and can be formed at very high positional anddimensional precisions.

The relative positional precision of the guide patterns 26 a, 27 a, 28a, 26 b, 27 b, and 28 b formed around the positioning portions 23, 24,and 25 to the coil patterns 16 a and 16 b is very high. By fitting thelocking members 29, 30, and 31 in the positioning portions 23, 24, and25, the coil 13 is attached to the slider 14 at high positionalprecision. The magnetic field generation center (coil pattern center) isconstant with respect to the slider 14, and does not vary. Hence, amagnetic field generated by the magnetic head 1 can be accuratelyapplied to the irradiation position of a recording beam on themagneto-optical disk 4.

Note that the formation positions and shapes of holes and a recessserving as the positioning portions, and those of guide patterns formedat their peripheral edges are not limited to Example 9 shown in FIGS.10A and 10B. The locking member to be fit in the positioning portionformed on the coil may be formed on not the slider but another magnetichead building member such as the core.

Comparative examples for Examples 1 to 9 will be described.

COMPARATIVE EXAMPLE 1

FIGS. 19A and 19B show the detailed structure of a coil 13 asComparative Example 1. FIG. 19A is a plan view when viewed from the top,and FIG. 19B is a plan view when viewed from the bottom. The structureexcept for conductor patterns formed in the ineffective region is thesame as that in Example 1 shown in FIGS. 1, 2A, and 2B, and adescription thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Comparative Example 1 will be described. Also inthis example, a region where the distance S from the outer edge of eachof coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined as afirst region A1 on both the upper and lower surface sides of the coil 13in accordance with inequalities 1, 2, and 3; a region where the distanceS satisfies 60 μm<S≦240 μm, as a second region A2; and a region wherethe distance S satisfies 240 μm<S, as a third region A3. In FIGS. 19Aand 19B, a broken line B1 represents the boundary between the first andsecond regions A1 and A2, and a broken line B2 represents the boundarybetween the second and third regions A2 and A3.

The dummy patterns 17 a and 17 b are formed from square-matrix-likeconductor patterns in the entire region A1 except for a region where thedistance S from the outer edge of each of the coil patterns 16 a and 16b satisfies S<20 μm. The square-matrix-like conductor patterns have awidth of 120 μm and a pitch of 165 μm. Terminals 19 a and 19 b areformed in the third region A3 on the upper surface side of the coil 13.

On both the upper and lower surface sides, the conductor occupationratio R of the conductor pattern is about 0.58 in the first region A1,and about 0.93 in the second region A2. The conductor occupation ratio Rof the conductor pattern is about 0.94 in the third region A3 on theupper surface side, and about 0.93 in the third region A3 on the lowersurface side.

In Comparative Example 1, the conductor occupation ratios R in the firstregion A1 and second region are higher than the ranges defined byinequalities 1 and 2.

COMPARATIVE EXAMPLE 2

FIGS. 20A and 20B show the detailed structure of a coil 13 asComparative Example 2. FIG. 20A is a plan view when viewed from the top,and FIG. 20B is a plan view when viewed from the bottom. The structureexcept for conductor patterns formed in the ineffective region is thesame as that in Example 1 shown in FIGS. 1, 2A, and 2B, and adescription thereof will be omitted.

The conductor patterns, i.e., dummy patterns 17 a and 17 b formed in theineffective region in Comparative Example 2 will be described. Also inthis example, a region where the distance S from the outer edge of eachof coil patterns 16 a and 16 b satisfies 0 μm≦S≦60 μm is defined as afirst region A1 on both the upper and lower surface sides of the coil 13in accordance with inequalities 1, 2, and 3; a region where the distanceS satisfies 60 μm<S≦240 μm, as a second region A2; and a region wherethe distance S satisfies 240 μm<S, as a third region A3. In FIGS. 20Aand 20B, a broken line B1 represents the boundary between the first andsecond regions A1 and A2, and a broken line B2 represents the boundarybetween the second and third regions A2 and A3.

The dummy patterns 17 a and 17 b are formed from square-matrix-likeconductor patterns in the entire region A1 except for a region where thedistance S from the outer edge of each of the coil patterns 16 a and 16b satisfies S<20 μm. The square-matrix-like conductor patterns have awidth of 30 μm and a pitch of 300 μm. Terminals 19 a and 19 b are formedin the third region A3 on the upper surface side of the coil 13.

On both the upper and lower surface sides, the conductor occupationratio R of the conductor pattern is about 0.09 in the first region A1,and about 0.19 in the second region A2. The conductor occupation ratio Rof the conductor pattern is about 0.22 in the third region A3 on theupper surface side, and about 0.19 in the third region A3 on the lowersurface side.

In Comparative Example 2, the conductor occupation ratio R in the thirdregion A3 is lower than the range defined by inequality 3.

Table 1 shows a list of the conductor occupation ratios R in therespective regions of actually manufactured coils 13 according toExamples 1 to 9 and Comparative Examples 1 and 2, the measurement valuesof electrical characteristics, flatness evaluation results, and amaximum modulation frequency fmax achievable in a magneto-opticalrecording apparatus using the coils 13.

TABLE 1 Characteristics in Examples and Comparative Examples ConductorOccupation Electrical Maximum Ratio R Characteristics Modulation RegionRegion Region Rp fr Frequency A1 A2 A3 (Ω) [MHz] Flatness fmax [MHz]Example 1 Upper Surface 0 0.60 0.63 1320 377 good 14 Lower Surface 00.60 0.60 Example 2 Upper Surface 0 0.56 0.59 1300 392 good 14 LowerSurface 0 0.56 0.56 Example 3 Upper Surface 0 0.64 0.67 1320 374 good 14Lower Surface 0 0.64 0.64 Example 4 Upper Surface 0 0.77 0.77 1290 372good 14 Lower Surface 0 0.77 0.77 Exatnple 5 Upper Surface 0 0.50 0.551300 395 good 14 Lower Surface 0 0.50 0.52 Example 6 Upper Surface 0 00.55 1310 401 good 14 Lower Surface 0 0 0.52 Example 7 Upper Surface0.28 0.50 0.55 1190 356 good 12 Lower Surface 0.28 0.50 0.52 Example 8Upper Surface 0.25 0.55 0.55 1160 362 good 12 Lower Surfacc 0.25 0.550.52 Example 9 Upper Surface 0 0.50 0.55 1330 393 good 14 Lower Surface0 0.50 0.52 Comparative Upper Surface 0.58 0.93 0.94 740 272 good 7Example 1 Lower Surface 0.58 0.93 0.93 Comparative Upper Surface 0.090.19 0.22 1300 388 poor 10 Example 2 Lower Surface 0.09 0.19 0.19

The electrical characteristics of the coil 13 were evaluated by an RFresistance Rp and self-resonance frequency fr measured between theterminals 19 a and 19 b. The RF resistance Rp is a resistance componentparallel to an inductance component L at a frequency of 20 MHz, and theself-resonance frequency fr is a frequency which maximizes an impedancemagnitude |Z|.

Based on these results, the present invention (Examples 1 to 9) iscompared with Comparative Example 1 to find that the flatness is fine inboth the present invention and Comparative Example 1. However, the RFresistance Rp is higher in the present invention than in ComparativeExample 1. This means that the RF loss caused by the influence of aneddy current induced within a conductor pattern formed in theineffective region is smaller in the present invention. Also, theself-resonance frequency fr is higher in the present invention than inComparative Example 1. This means that the electrostatic capacitancebetween the coil pattern and the conductor pattern formed in theineffective region is smaller in the present invention. As a result, themaximum modulation frequency fmax of the magnetic field achievable inthe magneto-optical recording apparatus adopting the present inventionis about 12 to 14 MHz. In Comparative Example 1, the achievable maximummodulation frequency fmax is about 7 MHz. To set the maximum modulationfrequency fmax of the magnetic field to 8 MHz or more, at least the RFresistance Rp and self-resonance frequency fr must be 800 Ω or more and290 MHz or more, respectively.

The present invention is compared with Comparative Example 2 to findthat the electrical characteristics are the same. However, in thepresent invention, the flatness is fine without any deformation in themanufacture. In Comparative Example 2, the reinforcing effect of aconductor pattern formed in the ineffective region is insufficient, thecoil readily deforms during manufacture, and the number of defectivedevices increases. Even if non-defective devices are screened, it isdifficult to bring the coil close to a magneto-optical recording medium.Although the electrical characteristics are the same as in the presentinvention, the achievable maximum modulation frequency fmax of themagnetic field is about 10 MHz which is lower than in the presentinvention.

In the present invention, the conductor occupation ratio R of aconductor pattern formed in the ineffective region of the coil isdefined on the basis of the distance from the coil pattern. Accordingly,a coil having fine electrical characteristics and flatness can beobtained, and the maximum modulation frequency of the magnetic field canbe increased.

EXAMPLE 10

Example 10 of the present invention will be described. FIGS. 13A and 13Bshow the structure of a magnetic head 1. FIG. 13A is a side sectionalview, and FIG. 13B is a bottom view. The magnetic head 1 is constitutedby a core 12 made of a magnetic material such as ferrite, a coil 13, aheat dissipation member 32, and a slider 14 which mounts them. Referencenumeral 4 denotes a magneto-optical disk serving as a magneto-opticalrecording medium.

The core 12 is made of a magnetic material such as ferrite with a flatshape, and its center has a projecting magnetic pole p1 with a prismshape. The coil 13 is flat, and its center has a square hole h1. Themagnetic pole p1 of the core 12 is inserted in the hole h1. The coil 13is mounted on the slider 14 together with the core 12. The slider 14 ismade of a resin material, ceramic material, or the like, and has asliding surface As or floating surface Af for sliding orfloating/gliding on the magneto-optical disk 4, so as to face themagneto-optical disk 4.

In Example 10, the coil 13 has the same structure as that in Example 1shown in FIGS. 2A and 2B, and a detailed description thereof will beomitted. The coil 13 may have the same structure as that described inany one of Examples 2 to 9 shown in FIGS. 3A and 3B to FIGS. 10A and10B.

The heat dissipation member 32 is made of a high-thermal-conductivitymetal material such as aluminum, and arranged, directly or via ahigh-thermal-conductivity adhesive or the like, in tight contact with adummy pattern 17 a formed on the upper surface of the coil 13. If theheat dissipation member 32 is shaped into a corrugated structure, e.g.including a plurality of fins, thereby increasing the surface area, asshown in FIGS. 13A and 13B, the heat dissipation efficiency can beincreased.

In recording an information signal, a current is supplied to coilpatterns 16 a and 16 b to generate an RF loss and heat in the core 12and coil patterns 16 a and 16 b. Since the dummy pattern 17 a and adummy pattern 17 b are made of a high-thermal-conductivity material suchas copper, heat generated in the core 12 and coil patterns 16 a and 16 bconducts to the heat dissipation member 32 via the dummy pattern 17 a,and dissipates into the air. Heat also conducts to the dummy pattern 17b, and dissipates into the air from the lower surface of the dummypattern 17 b. Rotation of the magneto-optical disk 4 generates an airflow near its surface. By bringing the dummy pattern 17 b close to themagneto-optical disk 4 while facing the disk 4, the heat dissipationefficiency can be increased.

Forming the dummy patterns 17 a and 17 b can effectively dissipate heatto reduce the temperature rise of the magnetic head 1.

A magneto-optical recording apparatus for recording an informationsignal on the magneto-optical disk 4 using the above-described magnetichead 1 will be explained. FIG. 15 shows the schematic arrangement of themagneto-optical recording apparatus. The magneto-optical disk 4 isconstituted by a substrate 40 made of a transparent resin material, amagnetic recording layer 41 formed on the substrate 40, and a protectionfilm 42. The magneto-optical disk 4 is rotated by a spindle motor 5 at apredetermined speed. On the upper surface side (side having theprotection film 42) of the magneto-optical disk 4, the magnetic head 1shown in FIGS. 11A and 11B, FIGS. 12A and 12B, or FIGS. 13A and 13B isheld by one end of an elastic support member 11. The sliding surface Asor floating surface Af of the magnetic head is pressed almost parallelagainst the surface of the magneto-optical disk 4. An optical head 2which faces the magnetic head 1 and converges recording and reproducingbeams to irradiate the magnetic recording layer 41 via the substrate 40of the magneto-optical disk 4 is arranged on the lower surface side ofthe magneto-optical disk 4. The support member 11 and optical head 2 arecoupled by a coupling member 3.

The coil 13 of the magnetic head 1 is connected to a magnetic head drivecircuit 6, which is connected to a recording signal producing circuit 7.The optical head 2 is comprised of a laser source, an optical systemsuch as an objective lens, an optical sensor for detecting reflectedlight, and the like. The laser source is connected to a laser drivecircuit 8; the optical sensor, to an amplifying circuit 9; and theamplifying circuit 9, to an information signal reproducing circuit 10.

Recording operation of an information signal will be described indetail. In recording an information signal, the spindle motor 5 rotatesthe magneto-optical disk 4. Then, the magnetic head 1 slides on orfloats/glides above the protection film 42 of the magneto-optical disk4.

An information signal to be recorded is input from an input terminal T1of the recording signal producing circuit 7. The recording signalproducing circuit 7 performs modulation such as coding for theinformation signal to produce a recording signal in synchronism with aclock signal, and outputs the recording signal to the magnetic headdrive circuit 6. The magnetic head drive circuit 6 supplies a currentmodulated by the recording signal to the coil 13 of the magnetic head 1.Accordingly, the magnetic head 1 generates, from the distal end of themagnetic pole p1, a magnetic field which changes between upper and lowerdirections in accordance with the information signal. The magnetic head1 vertically applies the magnetic field to the magnetic recording layer41 of the magneto-optical disk 4.

The laser drive circuit 8 supplies a recording DC current or a pulsecurrent in synchronism with a clock signal to the laser source of theoptical head 2. Then, a high-power recording beam which has a constantintensity or flicks like pulses is converged into a light spot, whichirradiates the magnetic recording layer 41 via the substrate 40 of themagneto-optical disk 4.

Since the temperature of the magnetic recording layer 41 rises todecrease its coercive force at the recording beam irradiated portion,magnetization is directed to the applied magnetic field. The temperatureof the magnetic recording layer 41 drops to increase its coercive forceapart from the irradiated portion of the recording beam. Then,magnetization is fixed to form a magnetized region corresponding to theinformation signal.

Reproducing operation of a recorded information signal will be explainedin detail. Also in reproducing a recorded information signal, thespindle motor 5 rotates the magneto-optical disk 4. Since the magnetichead 1 is not generally used for reproduction of an information signal,the magnetic head 1 need not slide on or float/glide above theprotection film 42 of the magneto-optical disk 4, and may be retractedto a position above the magneto-optical disk 4 so as to be separatedfrom the disk 4.

The laser drive circuit 8 supplies a reproducing DC current to the lasersource of the optical head 2. Then, a low-power reproducing beam isconverged into a light spot, which irradiates the magnetic recordinglayer 41 via the substrate 40 of the magneto-optical disk 4.

The polarization plane of the reflected beam, serving as an informationsignal, of the reproducing beam from a magnetized region is obtained bythe magneto-optical effect (Kerr effect), so that the polarization planerotates in accordance with the magnetization direction of the magnetizedregion. The optical system of the optical head 2 converts rotation ofthe polarization plane of the reflected beam into an intensity change.The optical sensor detects this intensity change, and outputs it as anelectrical signal. The detection signal is output from the optical head2. The detection signal is amplified by the amplifying circuit 9, andundergoes signal processing such as binarization and decoding by theinformation signal reproducing circuit 10. As a result, the informationsignal is reproduced and output from a terminal T2.

EXAMPLE 11

Example 11 of the present invention will be described. FIGS. 14A and 14Bare sectional views showing the structure of a magnetic head 1. Themagnetic head 1 is constituted by a core 12 made of a magnetic materialsuch as ferrite, a coil 13, a slider 14 which is made of a resinmaterial, ceramic material, or the like, and mounts the core 12 and coil13, and a hemispherical lens 22 having a projection p2 at the center onthe lower surface. Reference numeral 4 denotes a magneto-optical diskserving as a magneto-optical recording medium.

The lens 22 is arranged to converge, into a small light spot, arecording or reproducing beam for irradiating the magneto-optical disk 4from the optical head in recording or reproducing an information signalon or from the magneto-optical disk 4 using a magneto-optical recordingapparatus (to be described later). The core 12 is flat, and its centerhas a hole h2. The center of the coil 13 has a hole h1. The projectionp2 of the lens 22 is inserted in the hole h2 of the core 12 and the holeh1 of the coil 13.

The coil 13 has the same structure as that described in Example 1, and adetailed description thereof will be omitted.

A magneto-optical recording apparatus for recording an informationsignal on the magneto-optical disk 4 using the above-described magnetichead 1 will be explained. FIG. 16 shows the schematic arrangement of themagneto-optical recording apparatus. The magneto-optical disk 4 isconstituted by a substrate 40 made of a resin material, a magneticrecording layer 41 formed on the substrate 40, and a protection film 42made of a transparent material. The magneto-optical disk 4 is rotated bya spindle motor 5 at a predetermined speed. On the upper surface side(side having the protection film 42) of the magneto-optical disk 4, themagnetic head 1 is held by one end of an elastic support member 11. Thesliding surface As or floating surface Af of the magnetic head ispressed almost parallel against the surface of the magneto-optical disk4. An optical head 2 for converging recording and reproducing beams toirradiate the magnetic recording layer 41 via the lens 22 of themagnetic head 1 and the substrate 40 of the magneto-optical disk 4 isarranged above the magnetic head 1. The support member 11 and opticalhead 2 are coupled by a coupling member 3.

The coil 13 of the magnetic head 1 is connected to a magnetic head drivecircuit 6, which is connected to a recording signal producing circuit 7.The optical head 2 is comprised of a laser source, an optical systemsuch as an objective lens, an optical sensor for detecting reflectedlight, and the like. The laser source is connected to a laser drivecircuit 8; the optical sensor, to an amplifying circuit 9; and theamplifying circuit 9, to an information signal reproducing circuit 10.

Recording operation and reproducing operation of an information signalare the same as in Example 1. The spindle motor 5 rotates themagneto-optical disk 4. While the magnetic head 1 slides on orfloats/glides above the protection film 42 of the magneto-optical disk4, an information signal is recorded and reproduced.

In Example 11, the distal end of the projection p2 of the lens 22attached to the magnetic head 1 is brought very close to themagneto-optical disk 4, and the optical head 2 irradiates themagneto-optical disk 4 with a recording or reproducing beam via the lens22. The beam can be converged into a smaller light spot, therebyincreasing the information signal recording density. When the beam neednot be converged into a smaller light spot, the magnetic head 1 need notcomprise the lens 22. Alternately, the magnetic head 1 may or may notcomprise a member (e.g., glass plate) for transmitting a laser beam.

Even in this case, the optical head 2 is located above the magnetic head1, and a recording or reproducing beam irradiates the magnetic recordinglayer 41 via the protection film 42 of the magneto-optical disk 4. Torealize this arrangement, a recording or reproducing beam-transmittingportion, e.g., the hole h1 must be formed in the center of the coil 13,and the coil pattern must surround the beam-transmitting portion.

Also in Example 11, dummy patterns 17 a and 17 b are formed inineffective regions around coil patterns 16 a and 16 b. The thickness Tof the coil 13 is uniformly 160 μm on almost the entire surface.Compared to a case in which no dummy pattern is formed, the mechanicalstrength of the coil 13 increases. The coil 13 is rigid enough, and doesnot deform, e.g., bend when the coil 13 is bonded to the core 12,mounted on the slider 14, and fixed in manufacturing a magnetic head.Since the upper surface (surface facing the core 12) of the coil 13 isflat, its lower surface (surface facing the magneto-optical disk 4) doesnot deform, e.g., protrude or incline upon bonding to the core 12.

The dummy patterns 17 a and 17 b can dissipate heat generated by thecoil patterns 16 a and 16 b and core 12, thereby preventing thetemperature rise of the magnetic head. If the magnetic head 1 comprisesa heat dissipation member, like Example 10, the heat dissipationefficiency can be increased.

In Example 11, the coil 13 may have the same structure as that describedin Examples 2 to 8. As described in Example 9, the coil 13 and slider 14may comprise a positioning portion and a locking member, respectively.

INDUSTRIAL APPLICABILITY

As has been described above, in a flat coil component for a magnetichead according to the present invention, the ineffective region where aconductor pattern capable of supplying a current so as to flow aroundthe magnetic field generation center is not formed is divided into thefirst, second, and third regions A1, A2, and A3 on the basis of thedistance S from the outer edge of the coil pattern (outer edge of theeffective region). Conductor patterns are formed in the respectiveregions so as to simultaneously satisfy inequalities 1, 2, and 3. In thefirst region A1, no conductor pattern forms any closed loop.Consequently, the present invention provides a flat coil component for amagnetic head in which the mechanical strength, flatness, anddimensional precision are improved without degrading the electricalcharacteristics of the coil. Using this coil can prevent any deformationsuch as bending when the coil is bonded to the core, mounted on theslider, and fixed in manufacturing a magnetic head. If the coil patternis formed on the upper surface side of the coil to which another memberis bonded, and the conductor pattern is formed in the ineffective regionoutside the coil pattern, the lower surface of the coil facing themagneto-optical recording medium does not deform, e.g., protrude orincline upon bonding.

The present invention, therefore, implements a magnetic head having highrelative positional precision between the coil and the optical head andhigh distance precision between the coil and the magneto-opticalrecording medium. Even when the coil is downsized to reduce itsinductance, the magnetic field can be accurately applied to therecording beam irradiation position of the magneto-optical recordingmedium. This allows setting the magnetic field modulation frequency to 8MHz or more and increasing the information signal recording speed.

If the guide pattern is formed at the peripheral edge of the positioningportion in a coil having the positioning portion, the mechanicalstrength around the positioning portion increases. In fitting thepositioning portion on a locking member attached to another buildingmember, the coil does not deform, and the positional precision of thecoil can be further increased. By forming guide and coil patterns byphotolithography, the positioning portion can be formed at highpositional and dimensional precision. Even when the coil is furtherdownsized, the relative positional precision between the coil and theoptical head can be increased.

Heat generated in the coil pattern and core formed in the effectiveregion dissipates via the conductor pattern formed in the ineffectiveregion, which prevents the temperature rise of the magnetic head.Especially, a magnetic head having a heat dissipation member in tightcontact with the conductor pattern can attain higher dissipationefficiency.

The present invention can, therefore, reduce the temperature rise of themagnetic head caused by the RF loss of the core or coil pattern at ahigh magnetic field modulation frequency. The present invention canprevent a decrease in the saturation flux density Bs of the magneticmaterial forming the core, and a decrease in the strength of a magneticfield generated by the magnetic head. In addition, the present inventioncan prevent deformation of the building member of the magnetic head andany electrical insulation failure.

Thus, the present invention can increase the magnetic field modulationfrequency and information signal recording density, compared to theprior art.

What is claimed is:
 1. A magnetic head coil having a conductor patternmade of a conductive material film, wherein the conductor patternincludes a spiral coil pattern to which a current can be supplied toflow around a magnetic field generation center, and a conductor patternwhich is formed outside the coil pattern and cannot receive at least acurrent so as to flow around the magnetic field generation center, whereS is a distance from an outer edge of an outermost periphery of the coilpattern, and P is a pitch (or minimum value when the pitch is notconstant) of the coil pattern, a conductor occupation ratio (ratio of atotal area of all conductor patterns formed in a given region to a totalarea of the region) R of a conductor pattern formed outside the coilpattern simultaneously satisfies inequalities 1, 2, and 3, and theconductor pattern does not form any closed loop surrounding the coilpattern in a first region A1 given by inequality 1: Inequality 1:0≦R≦0.3 in the first region A1 where 0≦S≦1.5P Inequality 2: 0≦R≦0.8 in asecond region A2 where 1.5P<S≦6.0P Inequality 3: 0.3<R≦1 in a thirdregion A3 where 6.0P<S.
 2. A magnetic head coil according to claim 1,wherein in the first region A1 given by inequality 1, the conductorpattern formed outside the coil pattern is discontinuous conductorpatterns divided into at least two in a spiral direction of the coilpattern.
 3. A magnetic head coil according to claim 2, wherein all theconductor patterns divided into at least two have an interval of notless than 0.2P.
 4. A magnetic head coil according to any one of claims1, 2, and 3, wherein the conductor pattern formed outside the coilpattern has a periodic shape having a period of not less than P to notmore than 5P.
 5. A magnetic head coil according to any one of claims 1to 3, wherein the conductor pattern formed outside the coil patternincludes a conductor pattern formed along a peripheral edge of the flatcoil component for a magnet head.
 6. A magnetic head coil according toclaim 5, wherein the conductor pattern formed along the peripheral edgeof the magnetic head coil has a band shape, and is coupled to anotherconductor pattern.
 7. A magnetic head coil according to any one ofclaims 1 to 3, wherein the magnetic head coil has a positioning portion,and the conductor pattern formed outside the coil pattern includes aguide pattern formed at a peripheral edge of the positioning portion. 8.A magnetic head coil according to any one of claims 1 to 3, wherein themagnetic head coil has a hole for receiving a magnetic pole or alight-transmitting portion, and the coil pattern is formed around thehole or the light-transmitting portion.
 9. A magnetic head having a coilfacing parallel a magneto-optical recording medium, wherein the coil hasa conductor pattern made of a conductive material film, and theconductor pattern includes a spiral coil pattern to which a current canbe supplied to flow around a magnetic filed generation center, and aconductor pattern which is formed outside the coil pattern and cannotreceive at least a current so as to flow around the magnetic filedgeneration center, where S is a distance from an outer edge of anoutermost periphery of the coil pattern, and P is a pitch (or minimumvalue when the pitch is not constant) of the coil pattern, a conductoroccupation ratio (ratio of a total area of all conductor patterns formedin a given region to a total area of the region) R of a conductorpattern formed outside the coil pattern simultaneously satisfyinequalities 1, 2 and 3, and the conductor pattern does not form anyclosed loop surrounding the coil pattern in a first region A1 given byinequality 1: Inequality 1: 0≦R≦0.3 in the first region A1 where0≦S≦1.5P Inequality 2: 0≦R≦0.8 in a second region A2 where 1.5P<S≦6.0PInequality 3: 0.3<R≦1 in a third region A3 where 6.0P<S.
 10. A magnetichead according to claim 9, further comprising a core made of a magneticmaterial.
 11. A magnetic head according to claim 9, further comprising alens.
 12. A magnetic head according to claim 9, further comprising aheat dissipation member in tight contact with the conductor patternformed outside the coil pattern.
 13. A magneto-optical recordingapparatus having an optical head for irradiating a magneto-opticalrecording medium with light and a magnetic head for applying a magneticfield modulated by an information signal to the magneto-opticalrecording medium, wherein the magnetic head has a coil facing parallelthe magneto-optical recording medium and a conductor pattern made of aconductive material film, and the conductor pattern includes a spiralcoil pattern to which a current can be supplied to flow around amagnetic field generation center, and a conductor pattern which isformed outside the coil pattern and cannot receive at least a current soas to flow around the magnetic field generation center, where S is adistance from an outer edge of an outermost periphery of the coilpattern, and P is a pitch (or minimum value when the pitch is notconstant) of the coil pattern, a conductor occupation ratio (ratio of atotal area of all conductor patterns formed in a given region to a totalarea of the region) R of a conductor pattern formed outside the coilpattern simultaneously satisfy inequalities 1, 2 and 3, and theconductor pattern does not form any closed loop surrounding the coilpattern in a first region A1 given by inequality 1: Inequality 1:0≦R≦0.3 in the first region A1 where 0≦S≦1.5P Inequality 2: 0≦R≦0.8 in asecond region A2 where 1.5P<S≦6.0P Inequality 3: 0.3<R≦1 in a thirdregion A3 where 6.0P<S.
 14. A magnetic head coil according to claim 4,wherein the conductor pattern formed outside the coil pattern includes aconductor pattern formed along a peripheral edge of the flat coilcomponent for a magnet head.
 15. A magnetic head coil according to claim6, wherein the magnetic head coil has a positioning portion, and theconductor pattern formed outside the coil pattern includes a guidepattern formed at a peripheral edge of the positioning portion.
 16. Amagnetic head coil according to claim 7, wherein the magnetic head coilhas a hole for receiving a magnetic pole or a light-transmittingportion, and the coil pattern is formed around the hole or thelight-transmitting portion.
 17. A magnetic head according to claim 9,wherein the coil has a hole for receiving a magnetic pole or alight-transmitting portion, and the coil pattern is formed around thehole or the light-transmitting portion.
 18. A magnetic head according toclaim 10, further comprising a lens.
 19. A magnetic head according toclaim 11, further comprising a heat dissipation member in tight contactwith the conductor pattern formed outside the coil pattern.
 20. Amagneto-optical recording apparatus according to claim 13, said magnetichead having a heat dissipation member in tight contact with theconductor pattern formed outside the coil pattern.
 21. A magnetic headaccording to claim 9, wherein in the first region A1 given by inequality1 of the coil, the conductor pattern formed outside the coil pattern isdiscontinuous conductor patterns divided into at least two in a spiraldirection of the coil pattern.
 22. A magnetic head according to claim21, wherein in the coil, all the conductor patterns divided into atleast two have an interval of not less than 0.2P.
 23. A magnetic headaccording to claim 18, wherein in the first region A1 given byinequality 1 of the coil in the magnetic head, the conductor patternformed outside the coil pattern is discontinuous conductor patternsdivided into at least two in a spiral direction of the coil pattern. 24.A magnetic head according to claim 23, wherein in the coil of themagnetic head, all the conductor patterns divided into at least two havean interval of not less than 0.2P.